Increasing rendering time, how to solve?

Question

3D rendering

I have a specific project in Cinema 4D that hasn't been modified. However, earlier rendering of one frame took from 3 to 40 minutes (there were simply frames with a large number of reflections and lighting). Now the render increases in nightmarish numbers , I could not wait beyond three frames, because:

• first frame - instead of ~5 minutes - 1.5 hours;
  
• second frame - instead of ~5 minutes - 2 hours;
  
• the third frame - instead of ~5 minutes - 3 hours.
  

I render through the standard physical render!
Otherwise, the PC itself works without problems, of course, the PC is checked for all kinds of viruses, including miners!